You could probably keep it in there until it outgrows the 29gal (in terms of physical size and aggressive behavior); ultimately it will require a larger tank (75gal+ as these fish, which are actually a Sciaenochromis fryeri, get upwards of 8"). Also, these are a dimorphic species so the females aren't as colorful as the males (gender might not be readily apparent if acquiring one small s. fryeri).